00:01
So for this problem, we're considering an electron and a proton, and they each have this kinetic energy of one ev, one ev, one electron, one electron bolt.
00:14
And so we want to figure out how fast each one is moving.
00:18
So v equals question marks and background stuff to first answer this.
00:23
Let's get their masses.
00:25
So i remember the mass of the electron because it has 911 in it, 9 .11, 10 to the minus 31.
00:31
I feel like this number is just a very cohesive number.
00:35
Nines, threes, and ones.
00:37
Mass of a proton, i think it's 1 .67 times 10 to the minus 27.
00:43
Let me look at that.
00:46
Oh, i did remember it.
00:47
1 .67 times 10 of the minus 27.
01:01
Okay, so that's m .e.
01:04
And then that's m .p.
01:06
And finally, we need to get electron volts to joules.
01:10
So maybe to jewel.
01:13
So there's one electron full is 1 .6 times 10 to the minus 19 joules.
01:21
So i'll just go ahead and write that down.
01:33
And so, yeah, and then both of these have that same charge.
01:39
So, yeah, q is also 1 .6 times 10 to the minus 19 coulones.
01:48
So, okay, now i think that's all we basically need to do the problem.
01:52
So k -e equals 1 half mv squared.
01:58
V is therefore equal to 2 k -e over m square -rooted.
02:05
And so that's going to be the square root of, you know, just, i don't know, 2 times 1 and then convert it.
02:18
So i'm going to be kind of sloppy with the units, but it's like i'm plugging in this number here to convert the electron volts to jewels.
02:29
So yeah, leave that.
02:33
And then for let's do the v of the proton.
02:39
So that's going to be 1 .67 times 10 to the minus 27.
02:49
Oh yeah.
02:49
Let me make sure that this is clearly a two.
02:53
And when i plug that into a calculator, which i'll do right now, i'm not going to pause video.
02:59
It's a pretty quick calculation.
03:03
Oops.
03:06
So that's going to be the square root of 2 times 1 .6 times 10 of the minus 10 of the minus 19, all divided by 1 .67 times 10 to the minus 27.
03:20
So i got 13 ,800.
03:26
Just going to round there.
03:31
13 ,800 meters per second, pretty high.
03:37
And then v of the electron is the same thing, but we just want to plug in.
03:43
I'm not going to rewrite it, but we just want to plug in a different mass...